I believe the correct answer is sound waves. It is the sound waves that always need matter or a medium in order to propagate. Sound waves are mechanical waves that has different characteristics to electromagnetic waves which does not requires a medium to travel. Mechanical waves depend on the particles interaction for it to travel hence a medium is needed.
Answer:
it forms nitrogen gas if it reacts with hydrochloric acid.
The balanced chemical equation is:
<h3>2H₂SO₄ + Pb(OH)₄ —> Pb(SO₄)₂ + 4H₂O</h3>
Chemical equation can be balance by simply doing a head count of the different elements in the reactants and products to verified they are equal.
The equation given in the question above can be balanced as follow:
H₂SO₄ + Pb(OH)₄ —> Pb(SO₄)₂ + H₂O
There are 2 atoms of SO₄ on the right side and 1 atom on the left side. It can be balance by writing 2 before H₂SO₄ as shown below:
2H₂SO₄ + Pb(OH)₄ —> Pb(SO₄)₂ + H₂O
There are a total of 8 atoms of H on the left side and 2 atoms on the right side. It can be balance by writing 4 before H₂O as shown below:
2H₂SO₄ + Pb(OH)₄ —> Pb(SO₄)₂ + 4H₂O
Thus, the equation is balanced.
Learn more: brainly.com/question/24720057
We need to find mass number


Your answer is 40u
Unsaturated would be the correct answer.